1-Methyl phosphorinanes

Investigation of the conformational equilibrium of 1-methyl-phosphorinane (4) by low temperature and P-nmr shows a temperature dependence, favouring the equatorial methyl conformer at low temperature and the axial methyl one at room temperature (S.I. Featherman and L.D. Quin, J. Amer. chem. Soc., 1973, 95, 1699). 

Gallagher has reported a convenient synthesis of functionalized phosphorinans (102) by Michael addition of methyl hypophosphite to methyl acrylate, followed by base-induced cyclization.78... 

The addition of oxygen, sulphur, or selenium to 2-hydro-4-methyl-l,3,2-dioxa-phosphorinan proceeds stereospecifically.143... 

The same features exist at a reduced level for POCCH couplings in phosphorinanes and these are about 2-6 Hz for an equatorial proton at C-5, while it is less than 1 Hz for an axial proton. Similarly, coupling of phosphorus to an equatorial methyl at C-4 is 2 to 3 Hz while that to axial methyl is less than 1 Hz (1968>83) similar trends have been found in the corresponding phosphonates.<1969,52)... 

Another system, which is also allowed by IUPAC and is sometimes very convenient (but which should be avoided when official names are established by IUPAC and cited in Chemical Abstracts), is the so-called a -nomenclature, in which the term phospha indicates replacement of carbon by phosphorus, e.g. phosphacyclohexane = phosphorinane, and phosphabenzene = A3- phosphorin. Five-coordinate phosphorus compounds are called phos-phoranes. However, this name is also used for phosphorus ylides with a four-coordinate phosphorus and a more or less polar R3f—CX moiety or a d -p R3P=CX double bond, e.g. methylenetriphenylphosphorane = triphenylphosphorus methylene ylide or tri-phenylphosphonium methyl ylide, Ph3P=CH2 = Ph3P—CH2. 

An 0-18 isotopic shift on P-31 chemical shifts of epimeric 1, 3,2-dioxaphosphorinane esters (10) has been used to investigate the stereochemistry of hydroxide catalyzed hydrolysis in these aryl phosphorinane triesters. As shown in Scheme I the axial epimer of 2-(2,4-dinitrophenoxy)-2-oxo-trans-5,6-tetramethylene-l,3,2-dioxa-phosphorinane) 5a, was hydrolyzed in 0-18 enriched hydroxide. The cyclic diester, 8, was methylated with diazomethane in methanol. The P-31 NMR spectrum of the 0-18 labeled axial methyl phosporl-nane product, 2, showed three signals representing the unlabeled... 

Diethylamino-methyl)-l,3,2-dioxaphosphorinan-2-snlfid771 Zu 1,5 g (11 mmol) 2-Hydro-1,3,2(A°)-dioxa-phosphorinan-2-sulfid gibt man bei 0-2° 1,32 g (8,3 mmol) Bis-[diethylamino]-methan und erwarmt das Ge-misch 1 Stde. auf 60°. Dann wird das Diethylamin i. Vak. entfernt, der Ruckstand wird destilliert Ausbeute 1,45 g (78%) Sdp. 70-7370,008 Torr (1 Pa). 

Methyl-l-methylen-phospholan bzw. -phosphorinan liefem mit Oxiran oder Oxetan spirocyclische Tetraorganophosphorane14 ... 

The reaction of 2-methyl-, 2,5-dimethyl-, and 2,2,5--trimethyl-phosphorinan-4-one with hydrogen peroxide or potassium permanganate, or with sulphur or selenium in a suitable solvent on boiling affords the corresponding 1-oxide, -sulphide, or -selenide in good yield (I.N. Azerbaev et at., ibid., 1976, 47). For the preparation, reactions, and... 

The C-nmr spectra of 1-methyl- and 1-ethyl-phosphor-anin-4-one and derivatives and also that of phosphorinane-4,4--diols in water at 30° have been recorded, along with the P-nmr spectra and equilibrium compositions for the hydration of some phosphorinan-4-ones. Also recorded the ir-and uv-spectra for 1-ethylphosphorinan-4-one and its 1-oxide and 1-sulphide (J.J. Breen, S.O. Lee, and L.D. Quin, J. org. Chem., 1975, 0, 2245). P-nmr spectral data of 1-phenyl-phosphorian-4-one (K. Ramarajan, M.D. Herd, and K.D. Berlin, Phosphorus Sulphur, 1981, 11, 199). 

C-nmr spectral data have been used to show that 1-methyl-and 1-phenyl-phosphorinane and their 4-ones, related 1-oxides and 1-sulphides and 1,1-dimethylphosphorinanium salts, possess similar chair conformations to those of the analogous S, O, and N six-membered heterocycles (J.A. Hirsch and K. Banasiak,... 

The cis-trans isomerization of 4-methyl-2-oxo-2/T-l,3,2-dioxaphos-phorinans (123) and (124) has been studied by n.m.r. spectroscopy on a sample of 90% /ra j -phosphorinan. The reaction is first-order, with an activation energy lower than the inversion barrier in tertiary phosphines. In view of this, a mechanism involving deprotonation and inversion of the phosphite anion is proposed. 

Phosphorinane is a colourless, malodorous toxic liquid which readily inflames in air. It is configurationally more stable than piperidine, in which the two isomers can be interconverted by inversion at the N atom, at a temperature as low as -fiO C. At -SO C, when pyramidal inversions are slowed down, the methyl groups lie largely in the equatorial positions in methyl piperidine (95%) methylcyclohexane (99%) and methylphosphorinane (66%). 

The l-phenyl-4-phosphorinan ring (3) has a chair conformation with the phenyl group axial. This conformation is retained when the oxygen atom is replaced by two methyl groups. " Bond lengths are angles are normal. 

CsHsBrjOaP, Bis(bromomethyl)acetoxyphosphine oxide, 37B, 379 CsHsBrjOaP, 2a-Bromo-5p-bromomethyl-5a-methyl-2p-oxo-11,3,2-dioxa-phosphorinane, 34B, 380... 

C11H13OPS, 1-Phenyl-4-phosphorinanone 1-sulfide, 45B, 731 C11H13O2P, 1-Phenyl-4-phosphorinanone 1-oxide, 45B, 731 Cl 1H1 aC10i,P, 2-Phenoxy-5-chloromethyl-5-methyl-2-oxo-1, 3,2-dioxa-phosphorinane, 39B, 495... 

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